Speed limiter for hydraulic governor

ABSTRACT

An engine speed limiting system including a hydraulic governor responsive to a reference fluid pressure in a main conduit for providing a variable rate of fuel transfer, a pump for delivering fluid into the main conduit, a regulating valve for selectively adjusting the reference fluid pressure and a limiting valve which is biased by variable fluid pressure for another source to establish a maximum value for the reference fluid pressure.

Unite States atent Hammond et a1.

1 Feb. 29, 1972 [54] SPEED LIMITER FOR HYDRAULIC GOVERNOR [72] lnventors: James T. Hammond, Tremond; John H.

Parks, Peoria, both of 111.

[73] Assignee: Caterpillar Tractor Co., Peoria, 111.

[22] Filed: Sept. 4, 1970 [21] Appl. No: 69,705

[52] US. Cl. ..l23/140 FG, 123/198 D, 123/198 DB [51] Int. Cl ..F02d l/l2 [58] Field ofSearch ..123/139,139A,140,140FG,

123/140 MC,198 R, 198 DA, 198 DB [56] References Cited UNITED STATES PATENTS Rowe et al. ..123/l98 D Maxwellet al ..123/ 140 Miller et al. ..l23/198 DB Primary Examiner-Laurence M. Goodridge Attorney-Fryer, Tjensvold, Feix, Phillips & Lempio [57} ABSTRACT An engine speed limiting system including a hydraulic governor responsive to a reference fluid pressure in a main conduit for providing a variable rate of fuel transfer, a pump for delivering fluid into the main conduit, a regulating valve for selectively adjusting the reference fluid pressure and a limiting valve which is biased by variable fluid pressure for another source to establish a maximum value for the reference fluid pressure.

5 Claims, 2 Drawing Figures PAIENIEurwzs m2 3. 645,245

INVENTORS JAMES T. HAMMOND JOHN H, PARKS ATTORNEYS SPEED LIMITER FOR HYDRAULIC GOVERNOR A hydraulic governor of the type included within the following description is disclosed at greater length in U.S. Pat. No. 3,472,215, issued Oct. 14, I969 and assigned to the Assignee of the present invention.

The present invention relates to an engine speed limiting system wherein a hydraulic governor is associated with limiting means for establishing a maximum reference fluid pressure to which the governor is responsive. The limiting means is responsive to another source of variable fluid pressure, for example, such as lubricant for an engine with which the governor is amociated in order to limit engine speed when lubricant pressure is below a minimum level.

Damage often occurs to various components of governor regulated engines when the engine is permitted to operate at high speeds immediately after starting and before sufiicient lubricant is supplied to all necessary portions of the engine. Accordingly, it is an object of the present invention to provide a speed limiter for such engines, the speed limiter being effective to prevent high-speed operation when there is inadequate pressurization in the engine lubricating system.

It is also an object of the present invention to provide such a speed limiter which is effective to limit engine speed and power output automatically if the lubricant pressure should drop below a safe level during operation. This additional feature of the invention similarly prevents damage to various engine components which may not be adequately lubricated under such conditions. The speed limiter preferably permits the governor to regulate the engine for operation at reduced speed and power output so that a vehicle driven by the engine may be safely moved to a proper place for repairs while substantially reducing the possibility of damage within the engine due to inadequate lubrication.

It is a further object of the invention to provide an engine speed limiting system including a governor which is hydraulically responsive to a reference fluid pressure with a regulating valve for adjusting the reference fluid pressure and a limiting valve to establish a maximum value for the reference fluid pressure. Such a system permits the various components of the speed limiting system to operate with a minimum of moving parts. Since relatively simple valving components may be used within the speed limiting system, the present invention permits such a system to be compact and of relatively simple construction while being highly reliable over long periods of operation.

Other objects and advantages of the present invention are made apparent in the following description having reference to the accompanying drawing.

In the drawing:

FIG. 1 is a partially schematic representation, with parts in section, of an engine speed limiting system including a hydrau lic governor, a regulating valve and a limiting valve constructed and arranged in accordance with the present invention; and

FIG. 2 is a sectioned view of the limiting valve more clearly illustrating its internal construction.

A speed limiting system as illustrated in FIG. 1, includes a hydraulic governor 11, a fluid source or fuel transfer pump 12, a regulating valve 13 and a limiting valve 14. The pump 12 supplied fuel to the regulating valve 13 and governor 11 through a conduit 16. The regulating valve 13 adjusts the fluid at a selected reference value P, to which the governor 11 is responsive for establishing the rate of fuel transfer and accordingly regulating speed and power output of an associated engine (not shown).

The governor 11 is preferably of the type being completely illustrated and described by the above reference but it is noted that a governor within the present system may be of any hydraulic type which is responsive to a reference fluid pressure such as that established at P, by the valve 13. As illustrated in P16. 1 the governor includes a housing 17 which is in communication with the conduit 16, the regulating valve 13 and various portions of a metering system 18 for the governor as briefly described below.

Fluid from the housing 17, being established at the reference pressure P, by the valve 13, is communicated through an opening 21 to act upon a piston 22. The reference fluid pressure P, from the housing 17 is also communicated through a conduit 23 to an inlet 24 for a centrifugal valve 26 which is arranged for rotation with a fuel pump cam shaft 27. The centrifugal valve 26 establishes a control pressure P, which is communicated through a passage 28 to a spring chamber 29 for the piston 22. The two fuel pressures P, and P together with the spring 31, interact upon the piston 22 which functions in a manner more completely described by the reference to operate fuel injectors (not shown) for delivering fuel to the engine at a specific instant rate. The governor 11 is thus effective to regulate engine speed and power output in response to the reference pressure P, as established by the regulating valve 13.

The regulating valve 13 includes a valve member 41 which establishes the reference pressure P,. A load piston 42 arranged for interaction with the valve member 41 by means of a spring 43, is positioned by a lever 44 for changing the spring load on the valve member 41 and thus permitting adjustment of the reference pressure P,.

The limiting valve 14 is also in communication with the components described above through the conduit 16. The limiting valve 14 functions to provide a maximum limit for the reference pressure P, and thus to limit the rate of fuel transfer provided by the governor 11 under the influence of the regulating valve 13. To accomplish this function, the limiting valve 14 includes check valve means as described below which are biased by another variable fluid pressure in a conduit 51, the limiting valve thus being effective to maintain a maximum reference pressure P, in response to the other variable fluid pressure. Preferably, the conduit 51 is a portion of the lubricating system for the associated engine so that the reference pressure P, and the fuel transfer rate established by the governor 11 is limited during operating conditions when the lubricant pressure is below a safe operating level.

As illustrated in FIG. 2, the limiting valve 14 includes an inlet 52 for communicating reference fluid pressure from the conduit 16 across a valve seat 53 into a chamber 54 which is also in communication with an outlet passage 56. A flexible diaphragm 57 is arranged across the limiting valve housing 58 with one side 59 of the diaphragm being in communication with the chamber 54. The conduit 51 is in communication through another inlet 61 with an annular chamber 62 arranged on the opposite side 63 of the diaphragm 57.

The check valve means referred to above is illustrated in FIG. 2 as a ball 64 which is positioned adjacent the valve seat 53 by a spring 66. The spring 66 is arranged for interaction between the ball 64 and a rigid, flanged plate 67 positioned against the one side 59 of the diaphragm 57. The plate 67 is maintained in this position by another spring 68 arranged for interaction between the plate 67 and an annular face 69 formed by the housing 58.

The ball 64 and spring 66 operate as a bypass valve to limit the reference pressure P, and thus engine power and speed as adjusted by the governor 11 under influence of the valve 13. If the lever 44 is positioned to increase the reference pressure P, above a safe instant level as determined by pressure within the conduit 51, the ball 64 permits fluid to be dumped from the conduit 16 through the chamber 54 and the outlet 56 in order to limit the reference pressure P,. For example, when fluid pressure within the conduit 51 is above a selected level, it acts upon the diaphragm 57 and increases the spring load tending to seat the ball 64 and close off the inlet 52. However, when pressure in the conduit 51 is below the selected level, the spring load on the ball 64 is reduced so that relative excessive pressure in the conduit 16 is relieved across the chamber 54 and the outlet passage 56. Preferably, the outlet passage 56 is in communication with a fluid inlet 71 for the pump 12 by means of a conduit 72. The conduit 72 also provides a drain passage for regulating valve 13.

Within the system as described above, it may be noted that engine fuel is contained within the chamber 54 while lubricant is communicated to the chamber 62 on the opposite side of the diaphragm 57. To prevent intermixing of these two fluids, the diaphragm 57 is preferably formed with two annular 5 flanges 73 and 74 which are secured in spaced-apart relation by an annular adapter portion 76 of the housing 58 to form an intermediate chamber 77. A drain outlet 78 is provided for the intermediate chamber 77. Thus, if either side of the diaphragm 57 should be damaged, fluid leakage from either side of the diaphragm would be vented out of the limiting valve through the outlet 78.

What is claimed is:

1. An engine speed limiting system, comprising a hydraulic governor having an inlet for receiving a reference fluid pressure, the governor being responsive to the reference fluid pressure for varying the rate of fuel transfer to the engine,

a source of engine fuel under pressure which provides the reference fluid pressure, the source being in communication with the governor inlet through conduit means,

a regulating valve in communication with the conduit means for adjusting the reference fluid pressure, and

a limiting valve in communication with the source and governor inlet, the limiting valve including relief check valve means for communicating the common conduit with a drain and establishing a maximum valve for the reference fluid pressure, the limiting valve further comprising a flexible diaphragm arranged for interaction with the check valve means through spring means, one side of 30 the diaphragm being in communication with the check valve means, the other side of the diaphragm being in communication with a conduit for receiving engine lubricant under pressure.

2. The speed limiting system of claim 1 wherein an intermediate chamber is formed about the diaphragm by the limiting valve, the intermediate chamber being in communication with a drain to prevent fluid communication between opposite sides of the diaphragm.

3. An engine speed limiting system, comprising a hydraulic governor having an inlet for receiving a reference fluid pressure, the governor being responsive to the reference fluid pressure for varying the rate of fuel transfer,

a source of engine fuel under pressure which provides the reference fluid pressure, the source being in communication with the governor inlet through conduit means,

a regulating valve in communication with the conduit means for adjusting the reference fluid pressure, and

a limiting valve in communication with the source and governor inlet, the limiting valve including check valve means for establishing a maximum value for the reference fluid pressure, the limiting valve also being in communication with a conduit for receiving engine lubricant under pressure, the limiting valve including a housing having one inlet in communication with the conduit means and another inlet in communication with the conduit for receiving engine lubricant, the check valve means comprising a valve seat across which the one inlet is in communication with an outlet passage, a ball for engagement with the valve seat, a flexible diaphragm which receives the engine lubricant on one side thereof, spring means being arranged between the other side of the flexible diaphragm and the ball.

4. The speed limiting system of claim 3 wherein the flexible diaphragm has flanges extending radially outwardly from both ends, the flanges being secured to a portion of the housing to form an intermediate chamber with means for communicating the chamber to a drain.

5. The speed limiting system of claim 3 wherein the outlet passage is in communication with a fluid inlet for the fluid source. 

1. An engine speed limiting system, comprising a hydraulic governor having an inlet for receiving a reference fluid pressure, the governor being responsive to the reference fluid pressure for varying the rate of fuel transfer to the engine, a source of engine fuel under pressure which provides the reference fluid pressure, the source being in communication with the governor inlet through conduit means, a regulating valve in communication with the conduit means for adjusting the reference fluid pressure, and a limiting valve in communication with the source and governor inlet, the limiting valve including relief check valve means for communicating the common conduit with a drain and establishing a maximum valve for the reference fluid pressure, the limiting valve further comprising a flexible diaphragm arranged for interaction with the check valve means through spring means, one side of the diaphragm being in communication with the check valve means, the other side of the diaphragm being in communication with a conduit for receiving engine lubricant under pressure.
 2. The speed limiting system of claim 1 wherein an intermediate chamber is formed about the diaphragm by the limiting valve, the intermediate chamber being in communication with a drain to prevent fluid communication between opposite sides of the diaphragm.
 3. An engine speed limiting system, comprising a hydraulic governor having an inlet for receiving a reference fluid pressure, the governor being responsive to the reference fluid pressure for varying the rate of fuel transfer, a source of engine fuel under pressure which provides the reference fluid pressure, the source being in communication with the governor inlet through conduit means, a regulating valve in communication with the Conduit means for adjusting the reference fluid pressure, and a limiting valve in communication with the source and governor inlet, the limiting valve including check valve means for establishing a maximum value for the reference fluid pressure, the limiting valve also being in communication with a conduit for receiving engine lubricant under pressure, the limiting valve including a housing having one inlet in communication with the conduit means and another inlet in communication with the conduit for receiving engine lubricant, the check valve means comprising a valve seat across which the one inlet is in communication with an outlet passage, a ball for engagement with the valve seat, a flexible diaphragm which receives the engine lubricant on one side thereof, spring means being arranged between the other side of the flexible diaphragm and the ball.
 4. The speed limiting system of claim 3 wherein the flexible diaphragm has flanges extending radially outwardly from both ends, the flanges being secured to a portion of the housing to form an intermediate chamber with means for communicating the chamber to a drain.
 5. The speed limiting system of claim 3 wherein the outlet passage is in communication with a fluid inlet for the fluid source. 